Gas turbines often include a compressor, a number of combustors, and a turbine. Typically, the compressor and the turbine are aligned along a common axis, and the combustors are positioned between the compressor and the turbine in a circular array about the common axis. In operation, the compressor creates a compressed working fluid, such as compressed air, which is supplied to the combustors. A fuel is supplied to the combustor through one or more fuel nozzles and at least a portion of the compressed working fluid and the fuel are mixed to form a combustible fuel-air mixture. The fuel-air mixture is ignited in a combustion zone that is generally downstream from the fuel nozzles, thus creating a rapidly expanding hot gas. The hot gas flows from the combustor into the turbine. The hot gas imparts kinetic energy to multiple stages of rotatable blades that are coupled to a turbine shaft within the turbine, thus rotating the turbine shaft and producing work.
To increase turbine efficiency, modern combustors may be operated at high temperatures which generate high thermal stresses on various components disposed within the combustor. As a result, at least a portion of the compressed working supplied to the combustor may be used to cool the components before being mixed with the fuel for combustion. For example, many modern combustors may include a generally annular cap assembly that at least partially surrounds the fuel nozzles. The cap assembly generally provides structural support for the fuel nozzles and may at least partially define a flow path for the fuel-air mixture to follow just prior to entering the combustion zone. Certain cap assemblies include a generally annular cap plate that is disposed at a downstream end of the cap assembly and that is adjacent to the combustion zone.
Current cap assembly designs generally comprise of multiple complex components, thereby requiring complex manufacturing and assembly techniques. The complexity of the current cap assembly designs generally require multiple connection points such as welds joints or brazed joints, thereby increasing the probability of cycle fatigue and potentially limiting the life of the cap assembly. In addition, the complexity of the designs may significantly increase the time required to assemble and/or disassemble and/or repair the cap assembly, thereby resulting in additional labor costs and outage costs. Therefore, a cap assembly that requires fewer components and that may be less costly to assemble and/or repair would be useful.